Concurrent infection due to Shewanella putrefaciens and Mycobacterium marinum acquired at the beach

Shewanella putrefaciens, a rare human pathogen: A review from a clinical perspective

Shewanella putrefaciens is a gramnegative, facultatively anaerobic, rod shaped bacterium. It belongs to the class of the Gammaproteobacteria and was first described in 1931. S. putrefaciens is part of the marine microflora and especially present in moderate and warm climates. The bacterium is a rare oppurtonistic human pathogen associated mainly with intra-abdominal as well as skin and soft tissue infections. However, it has also been reported in association with more severe diseases such as pneumonia, intracerebral and ocular infections and endocarditis. In these cases the clinical courses are often associated with underlying, predisposing diseases and risk factors. For successful treatment of S. putrefaciens, a combination of appropriate local therapy, e.g. surgical treatment or drainage, and antibiotic therapy should be performed. Since multiple resistances to antibiotics are described, the results of the antimicrobial susceptibility testing must be considered for effective therapy as well. Furthermore, a main challenge in clinical practice is the accurate microbiological identification, and especially the correct differentiation between S. putrefaciens and S. algae. Under certain circumstances, Shewanella-infections can have severe, sometimes even fatal consequences. Therefore, we decided to present the current state of knowledge as well as further aspects with regard to future diagnostics, therapy and research.

Shewanella infection in humans: Epidemiology, clinical features and pathogenicity

The genus Shewanella consists of Gram-negative proteobacteria that are ubiquitously distributed in environment. As the members of this genus have rapidly increased within the past decade, several species have become emerging pathogens worldwide, attracting the attention of the medical community. These species are also associated with severe community- and hospital-acquired infections. Patients infected with Shewanella spp. had experiences of occupational or recreational exposure; meanwhile, the process of infection is complex and the pathogenicity is influenced by a variety of factors. Here, an exhaustive internet-based literature search was carried out in PUBMED using terms “Achromobacter putrefaciens,” “Pseudomonas putrefaciens,” “Alteromonas putrefaciens” and “Shewanella” to search literatures published between 1978 and June 2022. We provided a comprehensive review on the epidemiology, clinical features and pathogenicity of Shewanella, which will contribute a better understanding of its clinical aetiology, and facilitate the timely diagnosis and effective treatment of Shewanella infection for clinicians and public health professionals.

Isolation of Shewanella putrefaciens in an elderly man with subacute intestinal obstruction & appendicitis

Shewanella is Gram-negative motile bacillus, non fermentative and facultative anaerobe. Its natural habitat is all forms of water and soil, but has also been isolated from fish, dairy products, oils, and carcasses. Often found with microflora of the marine environment. Bacterial infections with Shewanella spp. are rare. The exposure to the marine environment, sea and diary food are considered as a risk factor for Shewanella spp. infection. Clinical infections seen are otitis, soft tissue infection, bacteremia, ear infection, eye infection, infective arthritis, osteomyelitis, infective endocarditis and peritonitis.

Implementation of a Zebrafish Health Program in a Research Facility: A 4-Year Retrospective Study

In the past two decades, zebrafish (Danio rerio)-based research has contributed to significant scientific advances. Still, husbandry and health programs did not evolve at the same pace, as evidenced by the absence of general guidelines. Health monitoring is essential to animal welfare, to permit animal exchanges across facilities, to contribute to robust experimental results, and for data reproducibility. In this study, we report a health program implemented in a zebrafish research facility to prevent, monitor, and control pathogen, and disease dissemination. This program includes quarantine, routine health screening of sentinels, and nonroutine screenings of retired animals and sick/moribund individuals. An extensive list of clinical signs, lesions, and pathogens was monitored based on: daily observation of fish, necropsy, histology, and bacterial culture. The results indicate that the combined analysis of sentinels with the evaluation of sick/moribund animals enables a comprehensive description not only of pathogen prevalence but also of clinical and histopathologic lesions of resident animals. The establishment of a quarantine program revealed to be effective in the reduction of Pseudoloma neurophilia frequency in the main aquaria room. Finally, characterization of the colony health status based on this multiapproach program shows a low prevalence of lesions and pathogens in the facility.

Bacteremia and empyema caused by Shewanella algae in a trauma patient

OBJECTIVE

To describe the first reported case of bacteremia and empyema caused by Shewanella algae and summarize the existing literature on Shewanella human infection.

CASE SUMMARY

A 25-year-old healthy male was shot through the chest into the abdomen and fled into an adjacent body of seawater. He underwent surgical repair of his injuries, including pleural decortication. Leukocytosis, bandemia, and copious yellow bronchorrhea led to cultures; piperacillin/tazobactam and vancomycin were started for broad-spectrum empiric management based on the local intensive care unit antibiogram. Blood and pleural fluid cultures revealed S algae. Sputum cultures grew methicillin-sensitive Staphylococcus aureus and Haemophilus influenzae. He was successfully managed with an empiric and then tailored antibiotic regimen.

DISCUSSION

Shewanella algae is a rare Gram-negative bacillus that has infrequently been reported to cause infection. It is found predominantly in men. Shewanella algae infections span bacteremia to necrotizing soft tissue infection and are associated with injury and seawater exposure. Shewanella is susceptible to the majority of third- and fourth-generation cephalosporins, aminoglycosides, chloramphenicol, erythromycin, aztreonam, and fluoroquinolones, but are less predictably susceptible to tetracycline and trimethoprim/sulfamethoxazole and carbapenem agents. Shewanella infection is associated with medical comorbidities, in particular, renal failure and cardiovascular disease.

CONCLUSIONS

To our knowledge, this is the first case report of bacteremia and empyema caused by S algae. Such a case involving a young healthy individual should encourage health care providers to be aware of the potential infections caused by unusual pathogens, and to employ appropriate empiric antibiotic therapy based on reported sensitivity profiles. Based on available susceptibilities, we recommend using a third or fourth-generation cephalosporin as first-line pharmacologic management with regimen de-escalation based on culture-derived data.

Human infection with Shewanella putrefaciens and S. algae: report of 16 cases in Martinique and review of the literature

Shewanella spp. are saprophytic bacteria that are part of the marine microflora in warm climates and are rarely pathogenic. However, Shewanella spp. infections are being increasingly reported, and there has been no comprehensive review of the literature describing these infections. This article reports 16 cases of Shewanella spp. infections in Martinique since 1997 and reviews another 239 cases reported in the literature since 1973. Patients experienced soft tissue infections, ear infection, or abdominal and biliary tract infections. A skin or mucosal portal of entry was found for 53% of the patients and exposure to the marine environment was reported for 44%; 79% of patients had an underlying condition. Bacteriema were frequent (28%). Most (87%) patients recovered, although ear infections can become chronic. Death occurred in 13% of the patients. Most Shewanella spp. isolates are susceptible to cefotaxime (95%), piperacillin and tazobactam (98%), gentamicin (99%), and ciprofloxacin (94%).

Emerging infections: shewanella - a series of five cases

Background:

Shewanella spp. are unusual cause of disease in humans; however, reports of Shewanella infections have been increasing. Shewanella is a ubiquitous organism that has been isolated from many foods, sewage, and both from fresh and salt water. Earlier it was named as Pseudomonas putrefaciens or Shewanella putrefaciens. There are several reports describing this organism causing human infections such as cellulitis, abscesses, bacteremia, wound infection, etc. It is oxidase and catalase-positive non-fermenter gram-negative rod that produces hydrogen sulfide.

Aims:

The study was conducted to identify Shewanella spp., which was wrongly reported as Pseudomonas spp.

Materials and Methods:

Clinical samples were cultured as per standard clinical laboratory procedure. We tested the non-lactose-fermenting colonies for oxidase positivity. Oxidase-positive colony was inoculated in triple sugar iron slant (TSI) to know the hydrogen sulfide production. Hydrogen sulfide positive colonies were further tested for citrate, urease, indole, and amino acid decarboxylation and acid and gas production from sugars.

Results:

Five isolates identified as Pseudomonas spp. during preliminary testing were proved to be Shewanella spp. on further testing.

Conclusions:

It will help in better understanding the epidemiology, pathogenesis and risk factors associated with these and prevention of the rare pathogenic organisms.

Outbreak of Shewanella algae and Shewanella putrefaciens infections caused by a shared measuring cup in a general surgery unit in Korea

OBJECTIVE

To control an outbreak of Shewanella algae and S. putrefaciens infections by identifying the risk factors for infection and transmission.

DESIGN

Matched case-control study.

SETTING

A university-affiliated tertiary acute care hospital in Seoul, Republic of Korea, with approximately 1,600 beds.

PATIENTS

From June 20, 2003, to January 16, 2004, a total of 31 case patients with Shewanella colonization or infection and 62 control patients were enrolled in the study.

INTERVENTIONS

Requirement to use single-use measuring cups and standard precautions (including hand washing before and after patient care and use of gloves).

RESULTS

S. algae or S. putrefaciens was isolated from blood, for 9 (29.0%) of 31 patients who acquired one of the organisms; from bile, for 8 (25.8%), and from ascitic fluid, for 8 (25.8%). The attack rate of this outbreak was 5.8% (31 patients infected or colonized, of 534 potentially exposed on ward A) and the pathogenicity of the two species together was 77.4% (24 patients infected, of 31 who acquired the pathogens). The estimated incubation period for Shewanella acquisition was 3-49 days. Using logistic analysis, we identified the following risk factors: presence of external drainage catheters in the hepatobiliary system (odds ratio [OR], 20; P < .001), presence of hepatobiliary disease (OR, 6.4; P < .001), admission to the emergency department of the hospital (OR, 2.9; P = .039), wound classification of "contaminated" or "dirty or infected" (OR, 16.5; P = .012), an American Society of Anesthesiologists score of 3 or higher (OR, 8.0; P = .006), duration of stay in ward A (OR, 1.1; P < .001), and, for women, an age of 60-69 years (OR, 13.3; P = .028). A Shewanella isolate was recovered from the surface of a shared measuring cup, and 12 isolates of S. algae showed the same pulsed-field gel electrophoresis pattern.

CONCLUSIONS

This Shewanella outbreak had a single-source origin and spread by contact transmission via a contaminated measuring cup. Shewanella species are emerging as potentially serious human pathogens in hospitals and could be included in hospital infection surveillance systems.

Shewanella soft tissue infection: case report and literature review

OBJECTIVE

To better understand the clinical characteristics of soft tissue infections caused by Shewanella in humans.

METHODS

We report a case of Shewanella soft tissue infection and review the English literature from a search of PubMed.

RESULTS

A total of 27 adults (mean age 61.1+/-16.0 years) with soft tissue infections caused by Shewanella were included for analysis. Limb involvement was found in 22 (81.5%) patients, while scalp, face, perineum, lacrimal sac, and abdominal wall involvement were each found in one patient. Chronic ulcer over the leg (14 cases (51.9%)), steroid use (four cases (14.8%)), and liver cirrhosis (three cases (11.1%)) were the major underlying conditions. Shewanella bacteremia was found in 14 out of 22 patients with soft tissue infections involving the limbs. Two patients died of septicemia, giving a mortality rate of 7.4%.

CONCLUSIONS

Shewanella soft tissue infections usually develop in immunocompromised patients with a preexisting cutaneous ulcer (particularly over the legs) after marine environment or seawater exposure. In view of the possible catastrophic consequences, education on the prevention of Shewanella soft tissue infections in at-risk people (e.g., the immunocompromised or elderly with a cutaneous ulcer) relating the need to avoid exposure to the marine environment or seawater may be of importance.

Treatment of Mycobacterium marinum cutaneous infections

Mycobacterium marinum is a non-tuberculous mycobacterium found in non-chlorinated water, with worldwide prevalence. It is the most common atypical Mycobacterium that causes opportunistic infection in humans. It presents as a solitary, red-to-violaceous plaque or nodule with an overlying crust or verrucous surface, or as inflammatory nodules or abscesses, usually in a sporotrichotic type of distribution. Deep infections may also occur. Although diagnosis is confirmed by isolation and identification of the organism in practice diagnosis remains largely presumptive based on clinicohistological features and the response to treatment. Polymerase chain reaction allows the routine early detection of the organism from a biopsy specimen. In the near future, it seems possible that histopathological examination might be greatly assisted by the rapidly improving possibilities with in vivo imaging. There have been many therapeutic modalities used effectively in the treatment of M. marinum infections. Spontaneous remission has also been reported in untreated infections and in immunocompetent hosts. However, there is no proven treatment of choice because M. marinum is naturally multi-drug resistant species and treatment is based primarily on the personal experience and preference of individual investigators, without the benefit of large studies. In superficial cutaneous infections minocycline, clarithromycin, doxycycline and trimethoprim-sulfamethoxazole as monotherapy are effective treatment options, but drug resistance varies and thereby combination therapy usually of two drugs may be required. Ciprofloxacin has shown considerable effectiveness. In cases of severe infections, including those with a sporotrichoid distribution pattern, a combination of rifampicin and ethambutol seems to be the recommended regimen. The use of isoniazid, streptomycin and pyrazinamide as empirical treatment options should be avoided. Surgical treatment is not usually recommended and must be cautiously applied. Cryotherapy, X-ray therapy, electrodesiccation, photodynamic therapy and local hyperthermic therapy have been reported as effective therapeutic alternatives. M. marinum infection should always be included in the differential diagnosis of all cases with poor-healing wounds in upper extremities and a history of exposure to aquariums.

Shewanella algae and Shewanella putrefaciens: clinical and microbiological characteristics

The occurrence of the two Shewanella species found in clinical specimens, Shewanella algae and Shewanella putrefaciens, correlates with the temperature and salinity of seawater. This means that Shewanella infections occur in warm climates or during especially warm summers in temperate climates. The infections described most commonly involve ears, skin and soft tissue, with or without bacteraemia. Primary bacteraemia with a fulminant course is also seen in immunocompromised patients. Important differential characteristics between the two species include the ability of S. algae to produce mucoid colonies with beta-haemolysis on sheep blood agar, to grow at 42 degrees C and in NaCl 6% w/v, and to reduce nitrite, and an inability to produce acid from maltose, all of which are in contrast to the characteristics of S. putrefaciens. Automated identification systems fail to differentiate between S. algae and S. putrefaciens, as S. algae is not included in the databases of these systems. Presumably for this reason, most Shewanella infections reported during recent years have been attributed to S. putrefaciens. However, when extensive phenotypic characterisation is performed, most human infections are seen to be caused by S. algae. As the two species seem to have different pathogenic potential for humans, correct identification is important, and this is possible in routine clinical microbiology laboratories.

[Opportunistic infections caused by Shewanella, new emergent bacteria]

Shewanella putrefaciens and Shewanella algae are Gram negative, nonfermentative and oxidative bacilli whose the main phenotypic feature is the production of hydrogen sulfide gas. Widespread in the environment, both S. putrefaciens and S. algae species are rare human bacteria although they are reported with increasing frequency as a cause of opportunistic infection in humans, such as skin and soft tissue infections and bacteremia. Chronic infections of the lower limbs and liver disease have been identified as risk factors for bloodstream infection, with a faster course and a poorer prognosis in the last case. S. algae appears to be more virulent than S. putrefaciens. Most human S. putrefaciens strains are isolated from bacterial flora, which puts to question its clinical significance. Molecular biology must be used for an adequate identification because S. algae can easily be mistaken for S. putrefaciens with usual tests.

Soft tissue infection and bacteremia caused by Shewanella putrefaciens

Shewanella putrefaciens is as yet rarely responsible for clinical syndromes in humans. However, a case involving multiple organs in an elderly male under treatment with appropriate steroids confirms that attention should be devoted to unusual pathogens.

Mycobacterium marinum infections

Mycobacterium marinum is a saprophytic mycobacteria capable of causing soft tissue infection in humans, usually acquired by inoculation. As with other mycobacterial infections, diagnosis may be difficult and recent developments in molecular biology are also being applied to atypical mycobacteria such as Mycobacterium marinum.